A key role in anaesthetic practice is gathering and assimilating information from a variety of sources to construct and maintain an accurate mental model of what is happening to the patient, a model that will influence subsequent decisions made by the anaesthetist on the patient’s behalf, as part of a larger team. Effective performance of this role requires a set of mental functions that place great demands upon the physiology and psychology of anaesthetists, functions that are vulnerable to a wide range of factors including those affecting team performance and those affecting the anaesthetist specifically. The number of tasks, their complexity, the physical and mental demands of the job, the underlying health and well-being of the anaesthetist and the environment and context within which the team attempt to meet the demands placed on them will influence the outcome of patient care.